Isotopic exchange between deuterium and 2,2-dimethylbutane on platinum/silica and palladium/silica

Journal Article · Sat Jan 01 04:00:00 EST 1983 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(83)90294-4· OSTI ID:6203704

Eskinazi, V; Burwell, Jr, R L

Isotopic exchange between deuterium and 2,2-dimethylbutane (neohexane) has been investigated on a series of Pt/SiO/sub 2/ (percentage exposed of metal, D/sub h/ = 6.3 to 81%) and Pd/SiO/sub 2/ (D/sub h/ = 13.8 to 96.7%) catalyst at temperatures in the vicinity fo 100/sup 0/C. Catalysts were investigated after three different pretreatments: standard: O/sub 2/,300/sup 0/; H/sub 2/,300/sup 0/; He,450/sup 0/ and H/sub 2/,450/sup 0/: O/sub 2/,300/sup 0/; H/sub 2/,450/sup 0/ and H/sub 2/,100/sup 0/: O/sub 2/,300/sup 0/; H/sub 2/,100/sup 0/. One might expect exchange into the methylene group to be subject to substantial steric hindrance from the adjacent t-butyl group and the degree of steric hindrance to be less at edge atoms than at atoms in (100) and (111) faces, i.e., relatively less on small crystallites than on larger ones. In general, the effect of D/sub h/ upon the relative yield of ethyl-d/sub 5/ in neohexane did not accord with this expectation. A possible explanation is that the bounding faces of the crystallites are defective and contain many vacancies which generate sites about equivalent to edge sites in the degree of hindrance. If so, usual tests of structure sensitivity could be seriously affected.

• Research Organization: Northwestern Univ., Evanston, IL
• OSTI ID: 6203704
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 79:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
ALKANES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHROMATOGRAPHY
COMPARATIVE EVALUATIONS
CONFORMATIONAL CHANGES
DEUTERIUM
ELEMENTS
GAS CHROMATOGRAPHY
HYDROCARBONS
HYDROGEN ISOTOPES
ISOTOPES
ISOTOPIC EXCHANGE
KINETICS
LIGHT NUCLEI
MASS SPECTRA
MEDIUM TEMPERATURE
METALS
MINERALS
MOLECULAR STRUCTURE
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM
PLATINUM METALS
QUANTITY RATIO
REACTION KINETICS
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPACE DEPENDENCE
SPECTRA
STABLE ISOTOPES
STEREOCHEMISTRY
SYNTHESIS
TRANSITION ELEMENTS